All my iOS related downloads (firmware updates and app downloads) are incredibly slow in iTunes. Right now, a single 70 MB app is an estimated 3 hours download making the transfer rate lousy 52 Kbit/s on an 8 MBit/s ADSL.

When I download my .ipsw firmware updates (400 - 600 MB) in a browser from a direct download link (appldnld.apple.com) the transfer rate is normal though.